1. Field of the Invention
This invention is directed to methods for treating the inflammatory component of brain disorders in mammalian patients, and more particularly for treating those neurological brain disorders in which reactive oxygen species play a significant role in the underlying inflammatory pathology.
2.State of the Art
The events that lead to neurological disorders with a significant inflammatory component (including myasthenia gravis, GBS, CIDP, and multiple sclerosis) are not clear, but the following sequential steps appear to be critical. (1) The breaking of tolerance, a process in which cytokines, molecular mimicry, or superantigens may play a role in rendering previously anergic T-cells to recognize neural autoantigens. (2) Antigen recognition by the T-cell receptor complex and processing of the antigen via the major histocompatibility complex class I or II. (3) Costimulatory factors, especially B7 and B7-binding proteins (CD28, CTLA-4) and intercellular adhesion molecule (ICAM-1) and its leukocyte function-associated (LFA)-1 ligand. (4) Traffic of the activated T cells across the blood-brain or blood-nerve barrier via a series of adhesion molecules that include selectins, leukocyte integrins (LFA-1, Mac-1, very late activating antigen (VLA)-4) and their counterreceptors (ICAM-1, vascular cell adhesion molecule (VCAM)) on the endothelial cells. (5) Tissue injury when the activated T cells, macrophages, or specific autoantibodies find their antigenic targets on glial cells, myelin, axon, calcium channels, or muscle.
In designing specific immunotherapy, the main components involved in every step of the immune response need to be considered. Targets for specific therapy in neurological disease include agents and treatments that (a) interfere or compete with antigen recognition or stimulation; (b) inhibit costimulatory signals or cytokines; (c) inhibit the traffic of the activated cells to tissues; and (d) intervene at the antigen recognition sites in the targeted organ.
Reactive oxygen species (ROS) are activated forms of oxygen, including superoxide anion (O2.−) and hydroxyl radicals (HO.) together with hydrogen peroxide (H2O2) and various unstable intermediates of lipid peroxidation. They are generated as a result of aerobic metabolism. Neuronal brain tissue is particularly susceptible to oxidative damage due its to high consumption of oxygen and its limited antioxidant defense system. Reactive oxygen species formation is thought to have an impact on synaptic plasticity, cell signaling and the aging process. An age-related increase in reactive oxygen species production has been demonstrated (Martin et al., 2000) and the accumulation of reactive oxygen species has also been shown to be increased in the hippocampus as a consequence of peripheral LPS administration (Vereker et al., 2000a). This is mimicked by IL-1β administration (Vereker et al., 2000b). O'Donnell and colleagues (2000) have reported parallel changes in reactive oxygen species formation and IL-1β production; reactive oxygen species formation was shown to cause an increase in IL-1β production while IL-1β has the ability to induce reactive oxygen species formation thus suggesting the existence of a positive feedback loop which is potentially damaging to cells.
Increased concentrations of IL-1β have also been closely linked with neuronal degeneration (Mogi et al., 1996; Tenneti et al., 1998).
Enhanced activity of the stress-activated kinase c-Jun NH2-terminal kinase (JNK) is associated with cell degeneration and death (Park et.al., 1996; Maroney et.al., 1998), and has been shown to be activated in the hippocampus by several agents, including hydrogen peroxide, an inducer of reactive oxygen species production, and pro-inflammatory cytokines.
Another example of a neuronal brain deficit induced by IL-1β and LPS, is the impairment of long term potentiation (LTP) in the hippocampus (Vereker et al 2000a; Murray & Lynch, 1998). LTP is a form of synaptic plasticity that was originally described in the hippocampus, a brain region that is particularly vulnerable to degeneration which is associated with cognitive dysfunction. On the basis of this and other observations, LTP has been proposed as a biological substrate for learning and memory (Bliss & Collingridge, 1993).
Certain neurological brain disorders such as Downs syndrome (Layton et.al., Kedziora et.al., Schuchmann et. al.), epilepsy, brain trauma (e.g. physical damage to the brain such as concussion)(Layton et. al., Wildburgur et. al., Trembovler et. al.) and Huntington's disease (chorea)(Green) are currently understood to involve inflammation of brain cells as a significant component of the underlying pathology of the disorder. This inflammation could be the consequence of one or more of a variety of biological processes, such as the generation of excess-amounts of inflammatory cytokines such as IL-1β and TNF-α, in the brain cells or other components of the brain tissue, perhaps associated with the presence of high concentrations of reactive oxygen species in the brain tissue, which correlates to high levels of tissue damage or exacerbation of the disease. Reactive oxygen species are one of the effectors of inflammation in tissue such as brain tissue.
Other neurological disorders which have a significant inflammatory component include Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating polyneuropathy (CIDP), myasthenia gravis (MG), dermatomyositis, polymyositis, inclusion body myositis, post stroke, neurosarcoidosis, vascular dementia, closed head trauma, vasospasm, subarachnoid hemorrhage, adrenal leukocytic dystrophy (storage disorders), inclusion body dermatomyostis, minimal cognitive impairment and duchenne muscular dystrophy.
Chronic inflammatory demyelinating polyneuropathy (CIDP) is a neurological disorder characterized by slowly progressive weakness and sensory dysfunction of the legs and arms. The disorder, which is sometimes called chronic relapsing polyneuropathy, is caused by damage to the myelin sheath of the peripheral nerves. CIDP can occur at any age and in both genders, is more common in young adults, and in men more so than women. The primary symptoms include slowly progressive muscle weakness and sensory dysfunction affecting the upper and lower extremities. Other symptoms may include fatigue; abnormal sensations including burning, numbness and/or tingling sensations (beginning in the toes and fingers); paralysis of the arms and/or legs; weakened or absent deep tendon reflexes (areflexia); and, aching pain affecting various muscle groups.
CIDP is closely related to the more common, acute demyelinating neuropathy known as Guillain-Barré syndrome (GBS). CIPD is considered the chronic counterpart of the acute disease GBS. CIDP is distinguished from GBS, chiefly by clinical course and prognosis. However, both disorders have similar clinical features, and both share the CSF albuminocytological dissociation and the pathological abnormalities of multi-focal inflammatory segmental demyelination with associated nerve conduction features reflecting demyelination.
Guilain-Barré Syndrome (GBS) is an acute predominately motor polyneuropathy with spontaneous recovery that may lead to severe quadriparesis and requires artificial ventilation in 20–30% of patients. The diseases that underlie this syndrome have been classified as acute inflammatory demyelinating polyneuropathy (AIDP), the most common form, acute motor and sensory axonal neuropathy (AMSAN), and acute motor axonal neuropathy (AMAN). Fisher syndrome is a cranial nerve variant of GBS which characteristically results in opthalmoplegia, ataxia and areflexia. GBS is often preceded by infection with either Campylobacterjejuni, which is most common, cytomegalovirus (CMV), Epstein-Barr virus or Mycoplasma pneumoniae. 
Autoimmune myasthenia gravis (MG) is a disorder of neuromuscular transmission leading to fluctuating weakness and abnormal fatigueability. Weakness is attributed to the blockade of acetylcholine receptors (AChRs) at the neuromuscular endplate by circulating autoantibodies, followed by local complement activation and destruction of acetylcholine receptors (Stangel et al, J. Neurol. Sci. 153(2):203–14 (1998)). AchR is expressed on regenerating myoblasts but in normal adult muscle the AChR is only expressed at the motor endplate. In patients with early onset MG however the thymic medulla is infiltrated by lymph node-like T cells and germinal centres and there are myoblast-like myoid cells in the thymic medulla which express AChR. Therefore the presentation of the AChR antigen by these cells or by myoblasts is likely to be involved in the disease process (Curnow et al, J. Neuroimmunol. 115(1–2):127–134 (2001)). In studies of experimental autoimmune myasthenia gravis (EAMG) the Th1 cytokine, INF-γ, has been shown to be involved in disease progression and has been reported to be capable of inducing the production by myoblasts of class I and II major histocompatibility antigens, AChR and ICAM-1. IL-1 has also been shown to play a role in EAMG where disruption of the IL-1 beta gene was shown to diminish acetylcholine receptor-induced responses (Garcia et al, J. Neuroimmunol 120(1–2):103–11 (2001); Stegall et al, J. Neuroimmunol. 119(2):377–386 (2001)).
The causes of inflammatory muscle diseases dermatomyositis, polymyositis and inclusion body myositis (IBM) are unknown, but immune mechanisms are strongly implicated. Although clinically and immunopathologically distinct, these diseases share three dominant histological features: inflammation, fibrosis and loss of muscle fibres. In dermatomyositis, the endomysial inflammation and muscle fiber destruction is preceded by activation of the complement system of plasma proteins, and deposition of membranolytic attack complex on the endomysial capillaries (Dalakas, Curr. Opin. Pharmacol. 1(3):300–306 (2001)). There is evidence that this attack may also involve the blood vessels in the dermis (Dalakas et al, Curr. Opin. Pharmacol. 9(3):235–239 (1996)). Transforming growth factor beta, shown to be overexpressed in the perimysial connective tissue in dermatomyositis, is down-regulated after successful immunotherapy and reduction of inflammation and fibrosis (Dalakas, Arch. Neurol. 55(12):1509–1512 (1998)).
In polymyositis and IBM the disease begins with the activation of CD8+ T cells. These cytotoxic T cells reach the endomysial parenchyma to recognise muscle antigen(s) associated with the upregulation of the major histocompatibility complex (MHC) I on muscle fibres. The autoinvasive T cells exhibit gene rearrangement of their T-cell receptors (TCR) and are specifically selected and clonally expanded in situ by heretofore previously unknown antigens. Muscle cells do not normally express MHC I and II but in cases of polymyositis and IBM over expression of MHC is an early event that can be detected even in areas remote from the inflammation. INFγ and TNFα, cytokines that induce MHC, have been found in patients with active polymyositis (Dalakas, Curr. Opin. Pharmacol. 1(3):300–306 (2001)).
No signs of apoptosis have been detected in patients with inflammatory myopathies and in fact two strong anti-apoptotic molecules have recently been found to be expressed in the muscle fibers. One is the Fas-associated death domain-like IL-1-converting enzyme inhibitory protein (FLIP) and the other human IAP (inhibitor of apoptosis protein)-like protein. The result of unsuccessful apoptotic clearance of inflammatory cells is likely to be the cause of the sustained chronic cytotoxic muscle fiber damage (Vattemi et al, J. Neuroimmunol. 111(1–2):146–151 (2000)).
Sarcoidosis is a multisystem chronic disorder with unknown cause and a worldwide distribution. Neurosarcoidosis is a complication of sarcoidosis involving inflammation and abnormal deposits in the tissues of the nervous system. Sudden, transient facial palsy is common with involvement of cranial nerve VII. Other manifestations include aseptic meningitis, hydrocephalus, parenchymatous disease of the central nervous system, peripheral neuropathy and myopathy. Intracranial sarcoid may mimic various forms of meningitis, including carcinomatous and intracranial mass lesions such as meningioma, lymphoma and glioma, based on neuroradiological imaging. A lumbar puncture may show signs of inflammation. Elevated levels of angiotensin converting enzyme may be found in the blood or CSF. Therapy consists of immunosuppressive agents and corticosteroids (Nowak et al, J. Neurol. 248(5):363–372 (2001); Stern et al, Arch. Neurol. 42(9):909–917 (1985)).
Vascular dementia (VaD) is the general term for dementia caused by organic lesions of vascular origin, such as cerebral infarction, intracerebral haemorrhage or ischemic changes in subcortical white matter. It is the most frequent cause of dementia after AD accounting for about 20% of cases and 50% in subjects over 80 years (Dib, Arch. Gerontol. Geriatr. 33(1):71–80 (2001); Parnetti et al, Int. J. Clin. Lab Res. 24(1):15–22 (1994)). The clinical distinction between AD and VaD may be difficult and there are standard guidelines for research studies. VaD and AD can co-exist as “mixed dementia” where the presence of cerebrovascular disease may worsen Alzheimer dementia. Traditionally AD is characterized by the insidious onset of memory loss, followed by a gradual progression to dementia in the face of normal findings on neurological examination. VaD on the other hand, is characterized by stepwise cognitive decline punctuated by episodes of stroke that are accompanied by focal deficits on neurological examination, and evidence of stroke on computed topography (CI) or magnetic-resonance imaging (Jagust, Lancet 358(9299):2097–2098 (2001)). It is assumed that the risk factors for stroke and vascular disease are also factors for VaD. These include hypertension, smoking, diabetes, obesity, cardiac rhythm disorders, hyperlipidaemia, hypercholesterolaemia and hyperhomocysteinaemia. The apolipoprotein E4 genotype is also considered as a risk factor for VaD, AD and ischemic stroke (Dib, Arch. Gerontol. Geriatr. 33(1):71–80 (2001)). Current treatments of vascular dementia include anti-platelet agents and/or surgery, and the treatment of cognitive symptoms (Parnetti et al, Int. J. Clin. Lab. Rews. 24(1):15–22 (1994)).
Head trauma is associated with a variety of physiological and cellular phenomena such as ischemia, increased permeability of the blood-brain barrier (BBB), edema, necrosis and motor and memory dysfunction (Moor et al, Neurosci. Lett. 316(3):169–172 (2001); Shohami et al, J. Neuroimmunol. 72(2):169–177 (1997)). Ischemia caused by the initial brain injury induces a cascade of secondary events and the release of excitatory amino acids (EAA) such as glutamate and aspartate. Alteration in the levels of ions and neuromodulators lead to oxidation and cellular membrane damage and ultimately cellular death (Stahel et al, Brain Res. Rev. 27(3):243–256 (1998)). Experimental models for closed head injury (CHI) developed in the rat show the spatial and temporal induction of IL-1, IL-6 and TNF-α gene mRNA transcription along with an induction of IL-6 and TNF-α activity in the rat brain (Shohami et al, J. Neuroimmunol. 72(2):169–177 (1997)). IL-1β has also been shown to be released and it is the presence of these cytokines along with damage to endothelial cells that result in disruption of the BBB integrity. This disruption allows the recruitment of neutrophils into the subarachnoid space (Stahel et al (1998)).
TNF-α has been identified in the brain in several pathological conditions and inhibitors of TNF-α such as dexanabinol (HU-211) have been shown to improve neurological outcome following CHI (Shohami et al, J. Neuroimmunol. 72(2):169–177 (1997)).
Cerebral vasospasm is delayed onset cerebral artery narrowing in response to blood clots left in the subaracbnoid space after spontaneous aneurysmal subarachnoid hemorrhage (SAH) (Ogihara et al, Brain Res. 889(1–2):89–97 (2001)). It is angiographically characterized as the persistent luminal narrowing of the major extraparenchymal cerebral arteries and affects the cerebral microcirculation and causes decreased cerebral blood flow (CBF) and delayed ischemic neurological deficits. A number of studies have demonstrated morphological changes in cerebral arteries after SAH. Smooth muscle cells showed necrotic changes, such as dense bodies, degeneration of mitochondria, condensed lysosomes and dissolution of nuclear substances and the appearance of cell debris (Sobey et al, Clin. Exp. Pharmacol. Physiol. 25(11):867–876 (1998)). The impaired dilator and increased constrictor mechanisms that occur after SAH may be caused by oxyhaemoglobin produced by erythrocytes that inactivates NO in the subarachnoid space. Alternatively it may be due to an impaired activity of soluble guanylate cyclase resulting in reduced basal levels of cGMP in cerebral vessels and so a reduced responsiveness to NO (Ogihara et al, Brain Res. 889(1–2):89–97 (2001)). Production of IL-6 and IL-8 in the cerebrospinal fluid following SAH has also been demonstrated. It is thought that IL-6 may play a particular role in vasospasm as in induced vasoconstriction in a canine cerebral artery (Osuka et al, Acta Neurochir 140(9):943–951 (1998)).
Duchenne muscular dystrophy (DMD) is one of the most common, inherited, lethal disorders in childhood. It is an X-linked neuromuscular disease that affects 1 in 3500 males. Progressive muscle weakness begins between 2 and 5 years of age and ultimately leads to premature death by respiratory or cardiac failure during the middle to late twenties. Approximately 30% of cases are due to spontaneous mutation of the dystrophin genes while the remainder are inherited (Spencer et al, Neuromuscul. Disord. 11(6–7):556–564 (2001)). DMD patients therefore lack the protein dystrophin which is an essential link in the complex of proteins that connect the cytoskeleton to the extracellular matrix (Alderton et al, Trends Cardiovascular Med. 10(6):268–272 (2000)). Although gene therapy is the only cure for DMD it is believed that immune interventions may slow the progress of the disease. The reason for this is that there is evidence that immune cell interactions with dystrophin-deficient muscle can contribute to cell death in dystrophinopathies. It has also been shown that the population of immune cells in dystbrophic muscle are not only different from those found that invade mechanically-damaged tissue; they are similar to those found in inflammatory disease such as polymyositis. Current research indicates that T cells may play a role in the pathology of dystrophin deficiency and that there may be an autoimmune component to the disease in which T cells are activated by a common antigen (Spencer et al, Neuromuscular Disord. 11(6–7):556–564 (2001)).
U.S. Pat. No. 5,834,030 (Bolton) describes a process for treating a patient to combat peripheral vascular disease, which comprises extracting an aliquot of the patient's blood, treating the blood aliquot extracorporeally with stressors such as an oxidative environment (ozone/oxygen gas mixture bubbled there through), incident UV light and an elevated temperature.
U.S. Pat. No. 5,980,954 (Bolton) describes similar processes for treating autoimmune diseases in mammalian patients.
It is an object of the present invention to provide a novel treatment or prophylaxis of neurological disorders which have a significant inflammatory component, such as chronic inflammatory demyelinating polyneuropathy and Guillain-Barré syndrome.
“Immune modulation therapy” as the term is used herein, is an ex vivo treatment protocol which involves exposure of autologous peripheral blood to combinations of at least two physicochemical stressors, namely heat, oxidative stress such as ozonation and electromagnetic radiation such as ultraviolet irradiation and subsequent administration of the treated blood to the patient, suitably by intramuscular injection. There is recent evidence that such immune modulation therapy suppresses contact hypersensitivity (Shivji et al., 2000) as well as demonstrating an attenuated hyperthermic response to immobilisation stress in spontaneously hypertensive rats (Kouamé et al., 1997) thus suggesting a possible protective role. In support of this is the report that following such immune modulation therapy a reduction in the relative number of pro-inflammatory TH1 cells and an increase in TH2 cells have been observed in humans, signifying a reduction in the inflammatory response (Rabinovitch et al., 1998).